what does the number on tires mean?

Question

like for example 205/40ZR16, i kno the last number is tire size but what does the rest mean?

Answer 1

The 205 is the width of the tire. The 40 is the aspect ratio of the sidewall. In this case the sidewall is 40% of the width. The Z is the speed rating that the tire is good for. The R means that it is a radial tire. The 16 means that it has a 16" rim size.

Answer 2

That tells you what size tire you have. Here is an example -


# Tire Size Designation - The speed rating symbol can be included as part of the tire size designation. For example the tire size P205/60HR15 has the following meaning:

* P - Passenger car tire
205 - Nominal section width in millimeters
60 - Nominal aspect ratio (section height-to-width ratio)
H - H speed rated tire ( 130 mph max. speed rating)
R - Radial tire construction
15 - Nominal rim diameter in inches

Answer 3

the last is the rim size the rest is an aspect ratio of height verses width from the rim to the outside of tire. that is why even thou a tire is the same size its NOT the same diameter or circumference so should not be mix matched with other brands or models of tires, especially on all wheel drive vehicles

Answer 4

Not an answer but a continuation of the question. How can you determine the outside diameter of the tire? Will those numbers tell me?

Answer 5

205 is the width of the tyre tread
40 is the height of the tyre wall
16 is the diameter of the wheel its fitted to
there is another figure that is quite important, its speed rating t-upwards is ok

Answer 6

Go to Discount Tire web site.... explains the differnet numbers
http://www.discounttire.com/dtcs/infoSidewall.dos